Question

Black holes in orbit around a normal star are detected from the earth due to the frictional heating of infalling gas into the black hole, which can reach temperatures greater than $10^{6} K$. Assuming that the infalling gas can be modelled as a blackbody radiator, then the wavelength of maximum power lies

• A. in the visible region
• B. in the X-ray region
• C. in the the microwave region
• D. in the gamma-ray region of electromagnetic spectrum

Answer 1

Answer: (B)

$\lambda_{m}T = 2.898 \times 10^{-3} mK$
$\lambda_{m} = \frac{2.9\times10^{-3}}{10^{6}} = 2.9\times10^{-9} \, m = 2.9 \, nm. $
It lies in the $X$-ray region of the electromagnetic spectrum.